The present invention relates to an elevator and more particularly to a traction machine for an elevator which is provided with a reduction gear that rotatably mounts spaced parallel shafts with gears being respectively secured thereon so as to be engaged with each other.
Firstly, a conventional traction machine for an elevator of this type will be explained with reference to FIGS. 1 to 3 of the attached drawings.
In the drawings the reference numeral 1 denotes beams installed in a machine room (not shown), reference numeral 2 denotes a traction machine platform supported on beams 1 through rubber vibration isolators 3, and reference numeral 4 denotes a reduction gear mounted to traction machine platform 2. Reduction gear 4 comprises a gear housing 4a of generally rectangular cross section, an output shaft 4b rotatively supported within the opposite walls of housing 4a, a first rotor 4c in the form of a helical gear fixedly secured to output shaft 4b, a bore 4d formed in one of the walls of housing 4a corresponding to a portion thereof where one end of output shaft 4b is to be supported, four projections 4e provided at equiangular intervals on the outer surface of the wall of housing 4a around the peripheral portion of bore 4d, a support member 4f having generally a cylindrical shape so as to be loosely fit within opening 4d with a sufficient gap being left therebetween and fixedly mounted therein a radial bearing to rotatably carry output shaft 4b at the one end, support member 4f having a square flange portion symmetrical with the cylindrical portion thereof on the outer surface, bolts 4g each screwed into respective projections 4e so as to push against the respective side edges of the flange of support member 4f, an intermediate shaft 4h arranged in parallel with output shaft 4b and spaced apart therefrom and rotatively supported at opposite ends by the respective opposite walls of housing 4a, a second rotor 4i in the form of a helical gear fixedly secured to intermediate shaft 4h and in mesh with first rotor 4c, a third rotor 4j in the form of a helical gear fixedly secured to intermediate shaft 4h and spaced apart from second rotor 4i, an input shaft 4k arranged in parallel with intermediate shaft 4h and spaced apart therefrom and rotatively supported at opposite ends by the respective opposite walls of housing 4a, and a fourth rotor 4l in the form of a helical gear fixedly secured to input shaft 4 k and in mesh with third rotor 4j. Reference numeral 5 denotes an electric motor mounted to housing 4a so as to drive input shaft 4k, an electromagnetic brake 6 being interposed therebetween. Reference numeral 7 denotes a traction sheave fixedly secured to output shaft 4b at the end opposite to support member 4f outside housing 4a, reference numeral 8 denotes a hoisting wire rope reeved around traction sheave 7, reference numeral 9 denotes an elevator car suspended from hoisting wire rope 8 at its one end, reference numeral 9a denotes a car sling, reference numeral 9b is a cab supported by car sling 9a through rubber vibration isolators 9c, and reference numeral 10 denotes a counter weight suspended from hoisting wire rope 8 at its other end.
Thus, upon energization of electric motor 5, the rotation of the motor transmitted to input shaft 4k is reduced by reduction gear 4 to be transmitted to traction sheave 7 through output shaft 4b in a known manner so that car 9 and counter weight 10 are moved in opposite directions through hoisting wire rope 8. In this case, unless the backlash of the first and second rotors 4c and 4i, etc. is appropriately adjusted, various difficulties such as pitching, abnormal vibration, etc. of car 9, abnormal noises, seizure of the gears, etc. may occur, resulting in abnormal abrasion and damage of the gears. Further, in the case where the adjustment of the meshing of the teeth of first and second rotors 4c and 4i is insufficient, abnormal abrasion of the teeth, etc. may result. In order to obviate these difficulties, in the conventional reduction gear, as stated above, it is so designed that one end of output shaft 4b is adapted to be displaced through support member 4f by moving it in a desired direction by means of the appropriate adjustment of bolts 4g, making the adjustment of the backlash, meshing conditions, etc. of the teeth of first and second rotors 4c and 4i possible.
However, in this arrangement the adjustment mechanism for the position of support member 4f relative to housing 4a by means of bolts 4g brings another disadvantage that since bolts 4g are subjected to a large load the load of traction sheave 7, i.e. the suspension load of hoisting wire rope 8, is limited by the maximum tolerable load of bolts 4g. Further, since on adjustment of the mesh, etc. of the teeth of first and second rotors 4c and 4i a displacement of several hundredths of a mm is necessary, the adjustment operation through standardized pitch bolts 4g is difficult and troublesome, thus revealing another disadvantage. On the other hand, if the bolts 4g have fine pitch threads it is very troublesome to displace support member 4f in any great amount, thereby dimenishing the workability of the device.
Laid-Open Japanese Patent Publication No. 113696/1981, filed on Feb. 12, 1980, laid-open on Sept. 7, 1981, entitled "A Traction Machine for an Elevator", discloses a traction machine which comprises a reduction gear provided with parallel shaft gears, a traction sheave, a brake means and a driving electric motor, but the reduction gear does not disclose a technique to support each end of at least one of the shafts by a pair of cylindrical support members which are provided with eccentric outer and inner peripheries, respectively, so as to be engaged with each other through these peripheries for the purpose of facilitating the adjustment of the distance between the two parallel shafts.